1. Field of the Invention
This invention relates to an address check system and more particularly to an address check system in a system such as a pay-TV system for controlling a plurality of receiving stations by a single or a few transmitting stations, and so improved as to prevent that each receiving station gets out of the control by the transmitting station due to change of the address of the receiving station.
2. Description of the Prior Art
The system for controlling the functions of a plurality of receiving stations by a single or a few transmitting stations in the wireless manner or in a wired signal transmitting manner has generally been so arranged that different user numbers (addresses) are previously allotted to respective stations. The transmitting station sends the addresses and control information, and each receiving station then acts upon the control information only when its own address is called otherwise it ignores the control information.
In such a system, however, if the address of a receiving station has changed due to the disorder of the apparatus thereof or due to the unexpected operation of the apparatus with the intention or negligence of the subscriber, the receiving station ceases to function under the control by the transmitting station. However, no address checking method capable of preventing such an undesirable problem has yet conventionally been adopted. Therefore, when the abovementioned problem occurs, it has been impossible to prevent the subscriber from tapping. It is a serious problem which cannot be ignored in operating such a system.